Dynamic time warping (DTW) [1]}, [2]} is to
compute the distance between two sequences by warping them locally to the
same length. It allows one-to-many mappings between sequences to “stretch”
a sequence or many-to-one mappings to “condense” a sequence. In this way,
DTW is naturally compatible with phase distortion invariance of sequential
data [3]}. Despite the simplicity of DTW, 1NN
classifier with DTW distance has been very successful in many applications,
such as video, image and audio etc. [4]}, [5]}, [6]}. It has
been a consensus that DTW may be the strongest distance measurements for
sequences [7]}, [8]}.
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